The present disclosure relates to a semiconductor device, and more particularly, to a temperature sensing circuit of a semiconductor device capable of modifying a temperature code to adjust a variation range of temperature code values measured by a temperature sensor according to a variation range of target temperature code values.
In semiconductor devices requiring refresh operations, such as a dynamic random-access memory (DRAM), leakage current generally increases with increases in temperature. The increased leakage current results in deterioration of maintaining data and reduction in data retention time.
Accordingly, DRAMs, for example, must refresh data stored in memory cells by themselves to continuously maintain the data of the memory cell. The refresh period may be changed in accordance with the temperature to reduce power consumption of the DRAM.
More specifically, the power consumption may be reduced by lengthening the refresh period in a low-temperature region among multiple temperature regions, and data loss may be prevented by shortening the refresh period in a high-temperature region. A temperature sensing circuit is therefore needed for sensing the internal temperature of the DRAM. In general, a temperature sensing circuit generates a 1-bit signal indicating whether a sensed temperature is higher or lower than a specific temperature, and a temperature code signal based on a digital result value proportional to the sensed temperature.
However, when the range of temperature codes output from a temperature sensing circuit does not correspond to the range of temperature codes required by a particular design or specification, for example, when the range of temperature codes output from the temperature sensing circuit is larger or smaller than the range of temperature codes required for the specification, the characteristics of a semiconductor device cannot be optimized. Thus, to adjust the variation range of temperature code values according to the variation range of target temperature code values required by the specification, a predetermined temperature code modification operation is needed.